1 /* Data flow functions for trees.
2 Copyright (C) 2001, 2002, 2003, 2004, 2005, 2007, 2008, 2009
3 Free Software Foundation, Inc.
4 Contributed by Diego Novillo <dnovillo@redhat.com>
6 This file is part of GCC.
8 GCC is free software; you can redistribute it and/or modify
9 it under the terms of the GNU General Public License as published by
10 the Free Software Foundation; either version 3, or (at your option)
13 GCC is distributed in the hope that it will be useful,
14 but WITHOUT ANY WARRANTY; without even the implied warranty of
15 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
16 GNU General Public License for more details.
18 You should have received a copy of the GNU General Public License
19 along with GCC; see the file COPYING3. If not see
20 <http://www.gnu.org/licenses/>. */
24 #include "coretypes.h"
27 #include "pointer-set.h"
30 #include "basic-block.h"
35 #include "langhooks.h"
38 #include "diagnostic.h"
39 #include "tree-dump.h"
41 #include "tree-flow.h"
42 #include "tree-inline.h"
43 #include "tree-pass.h"
48 /* Build and maintain data flow information for trees. */
50 /* Counters used to display DFA and SSA statistics. */
58 size_t max_num_phi_args;
64 /* Local functions. */
65 static void collect_dfa_stats (struct dfa_stats_d *);
66 static tree find_vars_r (tree *, int *, void *);
69 /*---------------------------------------------------------------------------
70 Dataflow analysis (DFA) routines
71 ---------------------------------------------------------------------------*/
72 /* Find all the variables referenced in the function. This function
73 builds the global arrays REFERENCED_VARS and CALL_CLOBBERED_VARS.
75 Note that this function does not look for statement operands, it simply
76 determines what variables are referenced in the program and detects
77 various attributes for each variable used by alias analysis and the
81 find_referenced_vars (void)
84 gimple_stmt_iterator si;
88 for (si = gsi_start_bb (bb); !gsi_end_p (si); gsi_next (&si))
90 gimple stmt = gsi_stmt (si);
91 if (is_gimple_debug (stmt))
93 find_referenced_vars_in (gsi_stmt (si));
96 for (si = gsi_start_phis (bb); !gsi_end_p (si); gsi_next (&si))
97 find_referenced_vars_in (gsi_stmt (si));
103 struct gimple_opt_pass pass_referenced_vars =
107 "*referenced_vars", /* name */
109 find_referenced_vars, /* execute */
112 0, /* static_pass_number */
113 TV_FIND_REFERENCED_VARS, /* tv_id */
114 PROP_gimple_leh | PROP_cfg, /* properties_required */
115 PROP_referenced_vars, /* properties_provided */
116 0, /* properties_destroyed */
117 TODO_dump_func, /* todo_flags_start */
118 TODO_dump_func /* todo_flags_finish */
123 /*---------------------------------------------------------------------------
125 ---------------------------------------------------------------------------*/
126 /* Create a new annotation for a _DECL node T. */
129 create_var_ann (tree t)
134 gcc_assert (TREE_CODE (t) == VAR_DECL
135 || TREE_CODE (t) == PARM_DECL
136 || TREE_CODE (t) == RESULT_DECL);
138 ann = GGC_CNEW (struct var_ann_d);
139 *DECL_VAR_ANN_PTR (t) = ann;
144 /* Renumber all of the gimple stmt uids. */
147 renumber_gimple_stmt_uids (void)
151 set_gimple_stmt_max_uid (cfun, 0);
154 gimple_stmt_iterator bsi;
155 for (bsi = gsi_start_bb (bb); !gsi_end_p (bsi); gsi_next (&bsi))
157 gimple stmt = gsi_stmt (bsi);
158 gimple_set_uid (stmt, inc_gimple_stmt_max_uid (cfun));
163 /* Like renumber_gimple_stmt_uids, but only do work on the basic blocks
164 in BLOCKS, of which there are N_BLOCKS. Also renumbers PHIs. */
167 renumber_gimple_stmt_uids_in_blocks (basic_block *blocks, int n_blocks)
171 set_gimple_stmt_max_uid (cfun, 0);
172 for (i = 0; i < n_blocks; i++)
174 basic_block bb = blocks[i];
175 gimple_stmt_iterator bsi;
176 for (bsi = gsi_start_phis (bb); !gsi_end_p (bsi); gsi_next (&bsi))
178 gimple stmt = gsi_stmt (bsi);
179 gimple_set_uid (stmt, inc_gimple_stmt_max_uid (cfun));
181 for (bsi = gsi_start_bb (bb); !gsi_end_p (bsi); gsi_next (&bsi))
183 gimple stmt = gsi_stmt (bsi);
184 gimple_set_uid (stmt, inc_gimple_stmt_max_uid (cfun));
189 /* Build a temporary. Make sure and register it to be renamed. */
192 make_rename_temp (tree type, const char *prefix)
194 tree t = create_tmp_reg (type, prefix);
196 if (gimple_referenced_vars (cfun))
198 add_referenced_var (t);
199 mark_sym_for_renaming (t);
207 /*---------------------------------------------------------------------------
209 ---------------------------------------------------------------------------*/
210 /* Dump the list of all the referenced variables in the current function to
214 dump_referenced_vars (FILE *file)
217 referenced_var_iterator rvi;
219 fprintf (file, "\nReferenced variables in %s: %u\n\n",
220 get_name (current_function_decl), (unsigned) num_referenced_vars);
222 FOR_EACH_REFERENCED_VAR (var, rvi)
224 fprintf (file, "Variable: ");
225 dump_variable (file, var);
228 fprintf (file, "\n");
232 /* Dump the list of all the referenced variables to stderr. */
235 debug_referenced_vars (void)
237 dump_referenced_vars (stderr);
241 /* Dump variable VAR and its may-aliases to FILE. */
244 dump_variable (FILE *file, tree var)
248 if (TREE_CODE (var) == SSA_NAME)
250 if (POINTER_TYPE_P (TREE_TYPE (var)))
251 dump_points_to_info_for (file, var);
252 var = SSA_NAME_VAR (var);
255 if (var == NULL_TREE)
257 fprintf (file, "<nil>");
261 print_generic_expr (file, var, dump_flags);
265 fprintf (file, ", UID D.%u", (unsigned) DECL_UID (var));
266 if (DECL_PT_UID (var) != DECL_UID (var))
267 fprintf (file, ", PT-UID D.%u", (unsigned) DECL_PT_UID (var));
269 fprintf (file, ", ");
270 print_generic_expr (file, TREE_TYPE (var), dump_flags);
272 if (TREE_ADDRESSABLE (var))
273 fprintf (file, ", is addressable");
275 if (is_global_var (var))
276 fprintf (file, ", is global");
278 if (TREE_THIS_VOLATILE (var))
279 fprintf (file, ", is volatile");
281 if (ann && ann->noalias_state == NO_ALIAS)
282 fprintf (file, ", NO_ALIAS (does not alias other NO_ALIAS symbols)");
283 else if (ann && ann->noalias_state == NO_ALIAS_GLOBAL)
284 fprintf (file, ", NO_ALIAS_GLOBAL (does not alias other NO_ALIAS symbols"
285 " and global vars)");
286 else if (ann && ann->noalias_state == NO_ALIAS_ANYTHING)
287 fprintf (file, ", NO_ALIAS_ANYTHING (does not alias any other symbols)");
289 if (cfun && gimple_default_def (cfun, var))
291 fprintf (file, ", default def: ");
292 print_generic_expr (file, gimple_default_def (cfun, var), dump_flags);
295 if (DECL_INITIAL (var))
297 fprintf (file, ", initial: ");
298 print_generic_expr (file, DECL_INITIAL (var), dump_flags);
301 fprintf (file, "\n");
305 /* Dump variable VAR and its may-aliases to stderr. */
308 debug_variable (tree var)
310 dump_variable (stderr, var);
314 /* Dump various DFA statistics to FILE. */
317 dump_dfa_stats (FILE *file)
319 struct dfa_stats_d dfa_stats;
321 unsigned long size, total = 0;
322 const char * const fmt_str = "%-30s%-13s%12s\n";
323 const char * const fmt_str_1 = "%-30s%13lu%11lu%c\n";
324 const char * const fmt_str_3 = "%-43s%11lu%c\n";
326 = lang_hooks.decl_printable_name (current_function_decl, 2);
328 collect_dfa_stats (&dfa_stats);
330 fprintf (file, "\nDFA Statistics for %s\n\n", funcname);
332 fprintf (file, "---------------------------------------------------------\n");
333 fprintf (file, fmt_str, "", " Number of ", "Memory");
334 fprintf (file, fmt_str, "", " instances ", "used ");
335 fprintf (file, "---------------------------------------------------------\n");
337 size = num_referenced_vars * sizeof (tree);
339 fprintf (file, fmt_str_1, "Referenced variables", (unsigned long)num_referenced_vars,
340 SCALE (size), LABEL (size));
342 size = dfa_stats.num_var_anns * sizeof (struct var_ann_d);
344 fprintf (file, fmt_str_1, "Variables annotated", dfa_stats.num_var_anns,
345 SCALE (size), LABEL (size));
347 size = dfa_stats.num_uses * sizeof (tree *);
349 fprintf (file, fmt_str_1, "USE operands", dfa_stats.num_uses,
350 SCALE (size), LABEL (size));
352 size = dfa_stats.num_defs * sizeof (tree *);
354 fprintf (file, fmt_str_1, "DEF operands", dfa_stats.num_defs,
355 SCALE (size), LABEL (size));
357 size = dfa_stats.num_vuses * sizeof (tree *);
359 fprintf (file, fmt_str_1, "VUSE operands", dfa_stats.num_vuses,
360 SCALE (size), LABEL (size));
362 size = dfa_stats.num_vdefs * sizeof (tree *);
364 fprintf (file, fmt_str_1, "VDEF operands", dfa_stats.num_vdefs,
365 SCALE (size), LABEL (size));
367 size = dfa_stats.num_phis * sizeof (struct gimple_statement_phi);
369 fprintf (file, fmt_str_1, "PHI nodes", dfa_stats.num_phis,
370 SCALE (size), LABEL (size));
372 size = dfa_stats.num_phi_args * sizeof (struct phi_arg_d);
374 fprintf (file, fmt_str_1, "PHI arguments", dfa_stats.num_phi_args,
375 SCALE (size), LABEL (size));
377 fprintf (file, "---------------------------------------------------------\n");
378 fprintf (file, fmt_str_3, "Total memory used by DFA/SSA data", SCALE (total),
380 fprintf (file, "---------------------------------------------------------\n");
381 fprintf (file, "\n");
383 if (dfa_stats.num_phis)
384 fprintf (file, "Average number of arguments per PHI node: %.1f (max: %ld)\n",
385 (float) dfa_stats.num_phi_args / (float) dfa_stats.num_phis,
386 (long) dfa_stats.max_num_phi_args);
388 fprintf (file, "\n");
392 /* Dump DFA statistics on stderr. */
395 debug_dfa_stats (void)
397 dump_dfa_stats (stderr);
401 /* Collect DFA statistics and store them in the structure pointed to by
405 collect_dfa_stats (struct dfa_stats_d *dfa_stats_p ATTRIBUTE_UNUSED)
408 referenced_var_iterator vi;
411 gcc_assert (dfa_stats_p);
413 memset ((void *)dfa_stats_p, 0, sizeof (struct dfa_stats_d));
415 /* Count all the variable annotations. */
416 FOR_EACH_REFERENCED_VAR (var, vi)
418 dfa_stats_p->num_var_anns++;
420 /* Walk all the statements in the function counting references. */
423 gimple_stmt_iterator si;
425 for (si = gsi_start_phis (bb); !gsi_end_p (si); gsi_next (&si))
427 gimple phi = gsi_stmt (si);
428 dfa_stats_p->num_phis++;
429 dfa_stats_p->num_phi_args += gimple_phi_num_args (phi);
430 if (gimple_phi_num_args (phi) > dfa_stats_p->max_num_phi_args)
431 dfa_stats_p->max_num_phi_args = gimple_phi_num_args (phi);
434 for (si = gsi_start_bb (bb); !gsi_end_p (si); gsi_next (&si))
436 gimple stmt = gsi_stmt (si);
437 dfa_stats_p->num_defs += NUM_SSA_OPERANDS (stmt, SSA_OP_DEF);
438 dfa_stats_p->num_uses += NUM_SSA_OPERANDS (stmt, SSA_OP_USE);
439 dfa_stats_p->num_vdefs += gimple_vdef (stmt) ? 1 : 0;
440 dfa_stats_p->num_vuses += gimple_vuse (stmt) ? 1 : 0;
446 /*---------------------------------------------------------------------------
447 Miscellaneous helpers
448 ---------------------------------------------------------------------------*/
449 /* Callback for walk_tree. Used to collect variables referenced in
453 find_vars_r (tree *tp, int *walk_subtrees, void *data ATTRIBUTE_UNUSED)
455 /* If we are reading the lto info back in, we need to rescan the
457 if (TREE_CODE (*tp) == SSA_NAME)
458 add_referenced_var (SSA_NAME_VAR (*tp));
460 /* If T is a regular variable that the optimizers are interested
461 in, add it to the list of variables. */
462 else if (SSA_VAR_P (*tp))
463 add_referenced_var (*tp);
465 /* Type, _DECL and constant nodes have no interesting children.
467 else if (IS_TYPE_OR_DECL_P (*tp) || CONSTANT_CLASS_P (*tp))
473 /* Find referenced variables in STMT. In contrast with
474 find_new_referenced_vars, this function will not mark newly found
475 variables for renaming. */
478 find_referenced_vars_in (gimple stmt)
482 if (gimple_code (stmt) != GIMPLE_PHI)
484 for (i = 0; i < gimple_num_ops (stmt); i++)
485 walk_tree (gimple_op_ptr (stmt, i), find_vars_r, NULL, NULL);
489 walk_tree (gimple_phi_result_ptr (stmt), find_vars_r, NULL, NULL);
491 for (i = 0; i < gimple_phi_num_args (stmt); i++)
493 tree arg = gimple_phi_arg_def (stmt, i);
494 walk_tree (&arg, find_vars_r, NULL, NULL);
500 /* Lookup UID in the referenced_vars hashtable and return the associated
504 referenced_var_lookup (unsigned int uid)
507 struct tree_decl_minimal in;
509 h = (tree) htab_find_with_hash (gimple_referenced_vars (cfun), &in, uid);
510 gcc_assert (h || uid == 0);
514 /* Check if TO is in the referenced_vars hash table and insert it if not.
515 Return true if it required insertion. */
518 referenced_var_check_and_insert (tree to)
521 struct tree_decl_minimal in;
522 unsigned int uid = DECL_UID (to);
525 h = (tree) htab_find_with_hash (gimple_referenced_vars (cfun), &in, uid);
528 /* DECL_UID has already been entered in the table. Verify that it is
529 the same entry as TO. See PR 27793. */
530 gcc_assert (h == to);
534 loc = (tree *) htab_find_slot_with_hash (gimple_referenced_vars (cfun),
540 /* Lookup VAR UID in the default_defs hashtable and return the associated
544 gimple_default_def (struct function *fn, tree var)
546 struct tree_decl_minimal ind;
547 struct tree_ssa_name in;
548 gcc_assert (SSA_VAR_P (var));
550 ind.uid = DECL_UID (var);
551 return (tree) htab_find_with_hash (DEFAULT_DEFS (fn), &in, DECL_UID (var));
554 /* Insert the pair VAR's UID, DEF into the default_defs hashtable. */
557 set_default_def (tree var, tree def)
559 struct tree_decl_minimal ind;
560 struct tree_ssa_name in;
563 gcc_assert (SSA_VAR_P (var));
565 ind.uid = DECL_UID (var);
568 loc = htab_find_slot_with_hash (DEFAULT_DEFS (cfun), &in,
569 DECL_UID (var), INSERT);
571 htab_remove_elt (DEFAULT_DEFS (cfun), *loc);
574 gcc_assert (TREE_CODE (def) == SSA_NAME && SSA_NAME_VAR (def) == var);
575 loc = htab_find_slot_with_hash (DEFAULT_DEFS (cfun), &in,
576 DECL_UID (var), INSERT);
578 /* Default definition might be changed by tail call optimization. */
580 SSA_NAME_IS_DEFAULT_DEF (*(tree *) loc) = false;
583 /* Mark DEF as the default definition for VAR. */
584 SSA_NAME_IS_DEFAULT_DEF (def) = true;
587 /* Add VAR to the list of referenced variables if it isn't already there. */
590 add_referenced_var (tree var)
593 gcc_assert (DECL_P (var));
595 /* Insert VAR into the referenced_vars has table if it isn't present. */
596 if (referenced_var_check_and_insert (var))
598 /* Scan DECL_INITIAL for pointer variables as they may contain
599 address arithmetic referencing the address of other
600 variables. As we are only interested in directly referenced
601 globals or referenced locals restrict this to initializers
602 than can refer to local variables. */
603 if (DECL_INITIAL (var)
604 && DECL_CONTEXT (var) == current_function_decl)
605 walk_tree (&DECL_INITIAL (var), find_vars_r, NULL, 0);
613 /* Remove VAR from the list. */
616 remove_referenced_var (tree var)
619 struct tree_decl_minimal in;
621 unsigned int uid = DECL_UID (var);
623 /* Preserve var_anns of globals. */
624 if (!is_global_var (var)
625 && (v_ann = var_ann (var)))
628 *DECL_VAR_ANN_PTR (var) = NULL;
630 gcc_assert (DECL_P (var));
632 loc = htab_find_slot_with_hash (gimple_referenced_vars (cfun), &in, uid,
634 htab_clear_slot (gimple_referenced_vars (cfun), loc);
638 /* Return the virtual variable associated to the non-scalar variable VAR. */
641 get_virtual_var (tree var)
645 if (TREE_CODE (var) == SSA_NAME)
646 var = SSA_NAME_VAR (var);
648 while (TREE_CODE (var) == REALPART_EXPR || TREE_CODE (var) == IMAGPART_EXPR
649 || handled_component_p (var))
650 var = TREE_OPERAND (var, 0);
652 /* Treating GIMPLE registers as virtual variables makes no sense.
653 Also complain if we couldn't extract a _DECL out of the original
655 gcc_assert (SSA_VAR_P (var));
656 gcc_assert (!is_gimple_reg (var));
661 /* Mark all the naked symbols in STMT for SSA renaming. */
664 mark_symbols_for_renaming (gimple stmt)
671 /* Mark all the operands for renaming. */
672 FOR_EACH_SSA_TREE_OPERAND (op, stmt, iter, SSA_OP_ALL_OPERANDS)
674 mark_sym_for_renaming (op);
678 /* Find all variables within the gimplified statement that were not
679 previously visible to the function and add them to the referenced
683 find_new_referenced_vars_1 (tree *tp, int *walk_subtrees,
684 void *data ATTRIBUTE_UNUSED)
688 if (TREE_CODE (t) == VAR_DECL && !var_ann (t))
690 add_referenced_var (t);
691 mark_sym_for_renaming (t);
694 if (IS_TYPE_OR_DECL_P (t))
701 /* Find any new referenced variables in STMT. */
704 find_new_referenced_vars (gimple stmt)
706 walk_gimple_op (stmt, find_new_referenced_vars_1, NULL);
710 /* If EXP is a handled component reference for a structure, return the
711 base variable. The access range is delimited by bit positions *POFFSET and
712 *POFFSET + *PMAX_SIZE. The access size is *PSIZE bits. If either
713 *PSIZE or *PMAX_SIZE is -1, they could not be determined. If *PSIZE
714 and *PMAX_SIZE are equal, the access is non-variable. */
717 get_ref_base_and_extent (tree exp, HOST_WIDE_INT *poffset,
718 HOST_WIDE_INT *psize,
719 HOST_WIDE_INT *pmax_size)
721 HOST_WIDE_INT bitsize = -1;
722 HOST_WIDE_INT maxsize = -1;
723 tree size_tree = NULL_TREE;
724 HOST_WIDE_INT bit_offset = 0;
725 bool seen_variable_array_ref = false;
727 /* First get the final access size from just the outermost expression. */
728 if (TREE_CODE (exp) == COMPONENT_REF)
729 size_tree = DECL_SIZE (TREE_OPERAND (exp, 1));
730 else if (TREE_CODE (exp) == BIT_FIELD_REF)
731 size_tree = TREE_OPERAND (exp, 1);
732 else if (!VOID_TYPE_P (TREE_TYPE (exp)))
734 enum machine_mode mode = TYPE_MODE (TREE_TYPE (exp));
736 size_tree = TYPE_SIZE (TREE_TYPE (exp));
738 bitsize = GET_MODE_BITSIZE (mode);
740 if (size_tree != NULL_TREE)
742 if (! host_integerp (size_tree, 1))
745 bitsize = TREE_INT_CST_LOW (size_tree);
748 /* Initially, maxsize is the same as the accessed element size.
749 In the following it will only grow (or become -1). */
752 /* Compute cumulative bit-offset for nested component-refs and array-refs,
753 and find the ultimate containing object. */
756 switch (TREE_CODE (exp))
759 bit_offset += TREE_INT_CST_LOW (TREE_OPERAND (exp, 2));
764 tree field = TREE_OPERAND (exp, 1);
765 tree this_offset = component_ref_field_offset (exp);
768 && TREE_CODE (this_offset) == INTEGER_CST
769 && host_integerp (this_offset, 0))
771 HOST_WIDE_INT hthis_offset = TREE_INT_CST_LOW (this_offset);
772 hthis_offset *= BITS_PER_UNIT;
774 += TREE_INT_CST_LOW (DECL_FIELD_BIT_OFFSET (field));
775 bit_offset += hthis_offset;
777 /* If we had seen a variable array ref already and we just
778 referenced the last field of a struct or a union member
779 then we have to adjust maxsize by the padding at the end
781 if (seen_variable_array_ref
784 tree stype = TREE_TYPE (TREE_OPERAND (exp, 0));
785 tree next = TREE_CHAIN (field);
786 while (next && TREE_CODE (next) != FIELD_DECL)
787 next = TREE_CHAIN (next);
789 || TREE_CODE (stype) != RECORD_TYPE)
791 tree fsize = DECL_SIZE_UNIT (field);
792 tree ssize = TYPE_SIZE_UNIT (stype);
793 if (host_integerp (fsize, 0)
794 && host_integerp (ssize, 0))
795 maxsize += ((TREE_INT_CST_LOW (ssize)
796 - TREE_INT_CST_LOW (fsize))
797 * BITS_PER_UNIT - hthis_offset);
805 tree csize = TYPE_SIZE (TREE_TYPE (TREE_OPERAND (exp, 0)));
806 /* We need to adjust maxsize to the whole structure bitsize.
807 But we can subtract any constant offset seen so far,
808 because that would get us out of the structure otherwise. */
809 if (maxsize != -1 && csize && host_integerp (csize, 1))
810 maxsize = TREE_INT_CST_LOW (csize) - bit_offset;
818 case ARRAY_RANGE_REF:
820 tree index = TREE_OPERAND (exp, 1);
821 tree low_bound, unit_size;
823 /* If the resulting bit-offset is constant, track it. */
824 if (TREE_CODE (index) == INTEGER_CST
825 && host_integerp (index, 0)
826 && (low_bound = array_ref_low_bound (exp),
827 host_integerp (low_bound, 0))
828 && (unit_size = array_ref_element_size (exp),
829 host_integerp (unit_size, 1)))
831 HOST_WIDE_INT hindex = TREE_INT_CST_LOW (index);
833 hindex -= TREE_INT_CST_LOW (low_bound);
834 hindex *= TREE_INT_CST_LOW (unit_size);
835 hindex *= BITS_PER_UNIT;
836 bit_offset += hindex;
838 /* An array ref with a constant index up in the structure
839 hierarchy will constrain the size of any variable array ref
840 lower in the access hierarchy. */
841 seen_variable_array_ref = false;
845 tree asize = TYPE_SIZE (TREE_TYPE (TREE_OPERAND (exp, 0)));
846 /* We need to adjust maxsize to the whole array bitsize.
847 But we can subtract any constant offset seen so far,
848 because that would get us outside of the array otherwise. */
849 if (maxsize != -1 && asize && host_integerp (asize, 1))
850 maxsize = TREE_INT_CST_LOW (asize) - bit_offset;
854 /* Remember that we have seen an array ref with a variable
856 seen_variable_array_ref = true;
865 bit_offset += bitsize;
868 case VIEW_CONVERT_EXPR:
875 exp = TREE_OPERAND (exp, 0);
879 /* We need to deal with variable arrays ending structures such as
880 struct { int length; int a[1]; } x; x.a[d]
881 struct { struct { int a; int b; } a[1]; } x; x.a[d].a
882 struct { struct { int a[1]; } a[1]; } x; x.a[0][d], x.a[d][0]
883 struct { int len; union { int a[1]; struct X x; } u; } x; x.u.a[d]
884 where we do not know maxsize for variable index accesses to
885 the array. The simplest way to conservatively deal with this
886 is to punt in the case that offset + maxsize reaches the
887 base type boundary. This needs to include possible trailing padding
888 that is there for alignment purposes.
890 That is of course only true if the base object is not a decl. */
894 /* If maxsize is unknown adjust it according to the size of the
897 && host_integerp (DECL_SIZE (exp), 1))
898 maxsize = TREE_INT_CST_LOW (DECL_SIZE (exp)) - bit_offset;
900 else if (seen_variable_array_ref
902 && (!host_integerp (TYPE_SIZE (TREE_TYPE (exp)), 1)
903 || (bit_offset + maxsize
904 == (signed) TREE_INT_CST_LOW (TYPE_SIZE (TREE_TYPE (exp))))))
907 /* ??? Due to negative offsets in ARRAY_REF we can end up with
908 negative bit_offset here. We might want to store a zero offset
910 *poffset = bit_offset;
912 *pmax_size = maxsize;
917 /* Returns true if STMT references an SSA_NAME that has
918 SSA_NAME_OCCURS_IN_ABNORMAL_PHI set, otherwise false. */
921 stmt_references_abnormal_ssa_name (gimple stmt)
926 FOR_EACH_SSA_USE_OPERAND (use_p, stmt, oi, SSA_OP_USE)
928 if (SSA_NAME_OCCURS_IN_ABNORMAL_PHI (USE_FROM_PTR (use_p)))